Golden Eagle

Golden Eagle

Aquila chrysaetos

L 28-35" / WS 72-89"

Golden Eagles are large birds, about the same size as Bald Eagle, and considerably larger than both N.A. vultures. They are found throughout the West in grasslands, sagebrush, and semi-open clearings in mountainous terrain. The breeding range extends from Alaska through the western United States and from Quebec to northern Newfoundland and Labrador in the East, where they are much less common. They nest almost exclusively on cliffs, but sometimes in large trees or on transmission structures. Golden Eagles are solitary, found alone or in pairs but never in large groups like Bald Eagle. They are highly territorial, maintaining a home range of several square miles, and have even killed smaller raptors that trespass, leaving them for vultures and coyotes to scavenge. They are aggressive towards intruding eagles, and escort them from their territory even outside the breeding season.

Golden Eagles prey mostly on medium-sized mammals (especially jackrabbits), but are capable of catching large mammals (even foxes) and birds (e.g., grouse, ptarmigan), which they hunt through a variety of tactics including low-level surprise-and-flush techniques, perch-hunting, and high elevation aerial stoops. It has been said that a Golden Eagle can stoop almost as swiftly as a Peregrine Falcon! Mated pairs will also hunt as a team, as one bird flushes prey out of hiding and the other unexpectedly overtakes it from another direction. Unlike Bald Eagles, Golden Eagles do not seek out carrion but will feed on dead things if the opportunity arises. Females are notably larger than males when the two are side-by-side. During courtship or when agitated, they give a shrill "seeachup, seeachup."

Ageing Golden Eagles to a specific year in the field can be difficult. Beginning birders assume that birds with white in the wings are juveniles, and birds with none are adults. However, some juveniles lack white in the wings altogether, and birds as old as 4 years can show obvious white in the wings. Ideal views of the tail pattern are often needed to age Golden Eagles accurately, and without this, many Golden Eagles (especially birds gliding overhead) remain unknown age.

Shape

Perched, appear massive but small-headed.

Extremely long, somewhat broad wings.

Wings pinch-in at the body, more buteo-like than Bald Eagle, especially juveniles and 2nd-year birds that are broader-winged than older birds.

Head smaller than Bald Eagle but larger than buteo.

Flight

Appear slow moving, soaring in wider circles than other raptors.

Soar with dihedral (sometimes as steep as Turkey Vulture), and glide with bowed wings or modified dihedral.

Steady, even in strong winds.

Display slow wing beats (shallower than Bald Eagle) that end abruptly into dihedral.

Highly maneuverable when chasing prey or defending territories.

Plumage

All ages are dark brown overall with golden nape; males and females are essentially identical in plumage. Eyes are dark brown to amber.

Adult has grayish banding on the flight feathers, and a dark trailing edge to the secondaries. The wings of adults (and older sub-adults) appear two-toned underneath similar to Turkey Vulture. The tail is dark with a few pale broad bands, or multiple narrow bands. Upperside shows a narrow, pale area along the upperwing coverts.

Juvenile has a white base to the tail and variable white patches in the wings. Some have little or no white in the wings. The white in the tail typically covers more than half the tail, but some have less white in the tail, others have nearly complete white tails. The upperwing coverts fade by spring and contrast the upperside but still differ from the narrow, mottled look of older birds.

Sub-adult (about 2-4 years old) has varying amounts of white in wings and tail. The pale area on the upperwings of 2nd-year birds is less obvious than on older birds and tail still has a white base. 3rd-and 4th-year birds have a mix of white-based and all dark tail feathers, making the tail appear split in half (3rd-year) or with small white patches on both sides (4th-year), and white in wings typically limited to the secondaries, or none at all by 4th-year. The white on the tail is only apparent with good views on older sub-adults. Careful scrutiny of all-dark birds is necessary as most are quickly assumed to be adults.

Migration

Mainly from February through April in spring, and October through December in fall.